| 摘要 |
PROBLEM TO BE SOLVED: To provide a ball screw capable of reducing or minimizing a lost motion caused by a ball biting action when a driving is reversed without producing any riding-over of the balls.SOLUTION: This ball screw is constituted in such a way that each of thread grooves 11, 21 of a screw shaft 1 and a nut 2 is a Gothic arc groove and used while being pressurized in advance through a double-nut pre-load system or a constant pressure pre-load system, a ball screw load is of only the pre-load and its value is 3 to 5% of a load rating, a contact angle α when a nut element clearance ΔDis not present is 40° to 50°, R ratio of the groove is 0.54 to 0.56, a starting angle βof a land chamfer 7 of the screw shaft 1 is 65° to 75° and an axial clearance sof the nut element is set in a range of 0.17%<s/D≤3.6% in respect to a ball diameter φDof the ball used.SELECTED DRAWING: Figure 2 |
